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There seems to be a great deal of confusion regarding IGF-1 levels and blood testing. In recent weeks, I have learned that IGF-1 testing is not the most accurate. The readings indicate the amount of FREE IGF-1 floating around. In order for IGF-1 to be effective, it must bind with "binding proteins" like IGFBP-3. So, we should be testing IGFBP-3 levels instead. The higher the IGFBP-3 levels, the more IGF-1 is being used by the body, and therefore, lower FREE IGF-1 floating around. Low IGF-1 levels are actually good (most athletes have low IGF-1 levels); but if your HGH output is low, then IGF-1 will be low and we will have come to the wrong conclusion. HGH output can be high, and you still have low FREE IGF-1 (because your binding protein levels are high). So, IGFBP-3 testing becomes most important.
